It is widely recognized that the function of a detergent additive material can be significantly impaired in a detergent composition by interaction between the additive material and other components of the composition. For example, enzymes, perfumes and bleach activators can be deleteriously effected by interaction with peroxy bleaches; cationic fabric conditioners can be deleteriously effected by interaction with anionic surfactants; and fluorescers can be deleteriously effected by interaction with peroxy bleaches or cationic surfactants. Moreover, the consumer acceptibility of a product can also be significantly reduced as the result of physical interactions between a detergent additive and other components of a detergent composition. For instance, a speckled detergent containing a water-soluble dye can lose its aesthetic appeal as a result of migration of the dye into the detergent base powder, an effect which can be significantly enhanced by the presence in the detergent composition of a nonionic surfactant component. Physical segregation problems in the case of abnormally-sized additive materials can also contribute to reduce aesthetic appeal and effectiveness of a detergent composition.
Numerous attempts have been made, of course, to improve the storage-stability characteristics of detergent additive materials such as bleach activators and the like, but such attempts have in general encountered only limited success. The main approach to the problem has been to protect the additive material from its hostile environment by agglomerating, coating or encapsulating the material with a non-hygroscopic, preferably hydrophobic material. Conventionally, organic materials have found the greatest favour as coating agents because such materials readily form a substantially cohesive and continuous plastic matrix in which the additive material can be embedded. British Patent Nos. 1,204,123, 1,441,416, and 1,395,006 are representative of this general approach. Unfortunately, however, protection of sensitive ingredients within an organic plastic matrix as practiced in the art can have a detrimental effect on the dispersibility or dissolution characteristics of the ingredient in water. This is of particular significance in the case of bleach activators because poor dispersibility can lead directly to problems of "pinpoint spotting" and fabric damage.
Accordingly, the present invention provides detergent additive compositions having improved storage stability together with excellent release and dispersibility characteristics in wash water. In particular, it provides detergent additive compositions comprising bleach activators which are stable to storage in bleach-containing detergent compositions but which disperse readily in water to provide effective low temperature bleaching performance. The invention also provides detergent additive compositions having improved physical and processing characteristics.